When the locking disc is blocked against a rotation in the unwinding direction of the safety belt in the frame, initially no safety belt can be withdrawn from the belt retractor. This ensures that a vehicle occupant who is wearing the safety belt, takes part as early as possible in a vehicle deceleration. In order to prevent the forces exerted here onto the vehicle occupant by the safety belt from assuming undesirably high levels, the energy absorption element makes possible a relative rotation between the belt spool and the locking disc when a particular traction force is exceeded in the safety belt. This is generally known under the designation “force limitation”.
It is also known that the extent of the relative rotation between the belt spool and the locking disc is to be limited. In this way, the maximum possible forward movement which a vehicle occupant undergoes during a force limitation function of the belt retractor, is limited to a value which is recognized as being non-critical. For this, it is known in the prior art to provide a pin on the belt spool, which after a relative rotation between the belt spool and the locking disc of slightly less than one revolution arrives in abutment against a detent which is provided on the locking disc. For geometric reasons, in such a construction the maximum possible relative rotation between the belt spool and the locking disc is limited to an angle range which corresponds to 360 degrees minus the angle range assumed by the pin and the angle range assumed by the detent.
The object of the invention consists in further developing a belt retractor of the type initially mentioned, to the effect that the prerequisite for a greater relative rotation between the belt spool and the locking disc is provided, whilst a reliable limitation of the relative rotation is maintained.